Circuit breaker



July 28, 1942. H. J. UNGAL 2,290,977

CIRCUIT BREAKER Filed Aug. 28, 1940 3 Sheets-Sheet l n: use

WITNESSES: INVENTOR July 28, 1942. J. LlNGAL 2,290,977

CIRCUIT BREAKER Filed Aug. 28, 1940 3 Sheets-Sheet 2 WITNESSES: INVENTORBY sz/ 7 ATTORNEY July 28, 1942. H. J. LINGAL 2,290,977

CIRCUIT BREAKER Filed Aug. 28, 1940 s Sheets- Sheet ,s

WITNESSES! INVENTOR t 4/7 jlzkz 42/ f BY j Patented July 28, 1942CIRCUIT BREAKER Harry J. Lingal, Wilkinsburg, Pa., assignor toWestinghouse Electric & Manufacturing Com.- pany, East Pittsburgh, Pa.,a corporation of Pennsylvania Application August 28, 1940, Serial No.354,535

13 Claims.

The invention relates to circuit breakers and more particularly to theoperating means and latching means therefor.

Circuit breakers of the type embodying a releasable operating memberadapted to be restrained by a latch to maintain the breaker closed, orin operative condition for closing, usually employ a latch checkingswitch operated by the latch to insure that the circuit breakeroperating mechanism is in operative latched condition ready for closingbefore the closing means can be energized. The latch checking switch isalso sometimes used to control the operation of a counting element ofthe reclosing relay. Considerable difliculty has been experienced inapplying latch checking switches to circuit breaker operating mechanismsdue to rebounding of the latches when they are returned from thereleased to the latching position. This rebounding causes the latchchecking switch to falsely open thereby falsely operating the countingdevice of the reclosing relay: As a result the reclosing relay may causea lesser number of automatic reclosing operations than the number forwhich it is set.

In the case of a single shot recloser, i. e. one which is set to produceonly a single automatic reclosing operation following tripping of thebreaker, the extra openings of the latch checking switch caused by therebound of the latch, delays automatic reclosing of the breaker longerthan is desired.

An object of the invention is the provision of a circuit breaker havinga releasable operating mechanism normally held in operative position bya latch, with a means for preventing rebound of the latch when it movesto latching position.

Another object of the invention is the provision of a circuit breakermechanism having a releasable latch biased to latching position and alatch checking control switch operated by the latch, with means forpreventing rebound of the latch to prevent false operation of the latchchecking switch.

In accordance with the invention a metal weight, of a mass approximatelyequal to the mass of the latch and the parts which move with the latch,is loosely or slidably attached to either the latch or one of the partswhich move with the latch. The weight is arranged so that when the latchstarts to rebound toward the released position the weight is stillmoving toward the latched position and due to its momentum and massovercomes and prevents the rebound motion of the latch.

The invention, both as to structure and operation, together withadditional objects and advantages thereof will be best understood fromthe following detailed description of one embodiment thereof when readin conjunction with the accompanying drawings, in which:

Figure 1 is a side elevational View of a circuit breaker mechanismconstructed in accordance with the invention, the position of the partsbeing shown an instant after the circuit breaker mechanism has beentripped, and the breaker being shown schematically.

Fig. 2 is a plan view of the circuit breaker operating mechanism, theparts being shown in the closed latched position,

Fig. 3- is an end elevational View of the circuit breaker operatingmechanism the parts being shown in the closed latched position.

Fig. 4 is an enlarged fragmentary view, partly in section, showing thelatching mechanism moving to the latching position an instant after thereleasable member has been automatically retrieved to its normalposition, and

Fig. 5 is a fragmentary view similar to Fig. 4 showing the latchingmechanism in the latched position and the releasable lever in theretrieved position.

Referring to the drawings, the circuit breaker comprises in generalcircuit interrupting means 5 which may be of conventional construction,and an operating mechanism therefor indicated generally at l. Thecircuit interrupting means 5 is indicated schematically as comprisingstationary contacts 9 and a cooperating movable bridging contact I Iconnected by a suitable linkage system shown schematically at I3 to theoperating rod l5 of the circuit breaker operating mechanism 1. I Thecircuit breaker operating mechanism 1, with the exception of itslatching means, is generally similar to the mechanism disclosed inPatent 2,144,502 to J. B. MacNeill et al., issued J anuary 17, 1939, andalso to the mechanism shown in the copending application of Lloyd W.Dyer, et al., Serial No. 294,048, filed September 9, 1939; both of whichare assigned to the assignee of the present invention. The operatingmechanism 1 comprises, in general, a fabricated metal frame H, on whichis mounted a closing solenoid It, a tripfree lever mechanism indicatedgenerally at 2| which normally serves to connect the movable circuitbreaker contact II to the closing solenoid IS, a latching mechanism 23for normally holding the trip free lever mechanism in operative orthrust-transmitting condition, and an electromagnetic trip device 25operable to move the latching mechanism to released position to causeopening of the breaker.

The closing solenoid l9 comprises a stationary core 21, a movable core29, and an operating winding 3| which when energized pulls the movablecore downwardly to effect a closing operation of the breaker.

The trip-free lever mechanism comprises a closing lever 33 consisting ofa pair of spaced parallel rigidly connected levers 35 pivoted at one endto the frame H by means of pivots 31, and a breaker lever 39, consistingof a pair of parallel rigidly connected levers 4| which are pivoted atone end by a pivot pin 43 to the closing lever 33 adjacent the free endthereof and disposed in the space between the levers 35 which comprisethe closing lever.

The closing lever 33 is connected intermediate its ends by links 45 tothe movable core 29 of the closing solenoid l9, and the breaker lever 39is pivotally connected intermediate its ends by a pivot pin 41 to thebreaker operating rod l5. The breaker lever 39 carries at its free end atrip-free roller 49 which extends transversely between the free ends ofthe levers 4| comprising the breaker lever, and this roller is adaptedto be normally engaged and held by the latching mechanism 23 to hold thecircuit breaker closed and also to hold the circuit breaker mechanism inoperative condition for closing when the mechanism is automaticallyreset following a tripping operation.

The movable contact ll of the circuit breaker is biased to open circuitposition by means of a relatively strong spring (not shown) so that whenthe breaker lever 39 is released by the latching mechanism, the circuitbreaker will be quickly moved to open circuit position. The closinglever 33 is biased in a counterclockwise direction about its pivot axis31 by a pair of retrieving springs 5| positioned between the levers 35and the frame |1. These springs serve to move the closing lever to openposition when the closing lever is released during a tripping operationto cause clockwise movement of the breaker lever 39 about the pivot 41as a fulcrum to return the trip free roller 49 to the normal or latchedposition where it is reengaged by the latching mechanism 23. When thetrip free roller 49 and the breaker lever 39 are thus reset to latchedposition and engaged by the latching mechanism 23, the breaker lever 39is reconnected to the closing lever 33 for movement thereby so that thebreaker will be reclosed when the closing solenoid is energized.

A latch 53 is pivotally mounted on the frame |1.by a pivot pin 55 and isbiased by a spring 51 to latching position for engaging a roller 59carried by the closing lever 33 to hold the closing lever in closedposition. The latch 53 is adapted to be moved to released position by across bar Bl on the breaker lever 39 during the opening movement of thebreaker lever 39, thereby allowing the retrieving springs 5| toautomatically reset the mechanism following each tripping operation.

When the circuit breaker is held latched in the closed circuit position,the trip free roller 49 is held down by the latching mechanism 23 in aposition of alignment with the pivot axis 31 of the closing lever 33,and the closing lever 33 is also held latched down in the closedposition by the holding latch 53. In this closed position, the levers 33and 39 are in alignment with each other. When the trip device 25, whichis preferably a shunt trip, is energized either by the operation ofsuitable fault responsive relays, or by the closing of a manuallycontrolled shunt trip circuit, the latching mechanism is thereby causedto move to the released position effecting release of the trip freeroller 49 and the breaker lever 39. The movable contact ll of thecircuit breaker being no longer held in closed position is quickly movedto open circuit position by its biasing spring and in doing so moves thebreaker lever 39 in a clockwise direction about its pivot 43 to the openposition shown in Fig. 1. During the movement of the breaker lever 39 toopen position, the cross bar 6| thereof engages and moves the holdinglatch 53 to the released position effecting release of the free end ofthe closing lever 33. The retrieving springs 5| then move the closinglever counterclockwise about its fixed pivot axis 31 to open positionindicated by the dotted lines in Fig. 1. This opening movement of theclosing lever 33 moves the breaker lever 39 in a counterclockwisedirection about the pivot pin 41 as a fulcrum to return the trip freeroller 49 to the latched position where it is reengaged by the latchingmechanism 23. Both levers 33 and 39 now occupy the position indicated bythe dotted lines in Fig. l and the mechanism is reset and ready to bereclosed. When the solenoid I9 is energized to reclose the breaker, thetwo levers 33 and 39 are rotated together in a clockwise direction aboutthe pivot axis 31, to closed position, and the roller 59 of the closinglever is reengaged and latched by the holding latch 53 to hold theclosing lever in closed position.

The latching mechanism 23 comprises a latch 63 pivotally mounted on theframe l1 by a pivot pin 65 and having a latch projection 61 for engagingthe trip free roller 49 of the breaker lever 39 to hold the roller 49and the lever 39 in latched position. The latch 63 also comprises a pin69 adjacent the free end which pivotally supports one member 1| of atoggle; the other member 13 of the toggle being pivotally mounted on theframe H by means of a rotatable shaft 15 to which the member 13 isrigidly clamped at its lower end by screws 11. The shaft 15 is rotatablymounted in bearings 19 provided there for on the frame I1, and one endof the shaft extends laterally beyond the side of the frame 11 as shownin Figs. 2 and 3. The adjacent ends of the toggle members 1| and 13 arepivotally connected together by a knee pivot pin 8|.

A tension spring 83 is connected at one end to the toggle member 13adjacent the knee of the toggle and this spring serves to bias the latch63 to latching position and the toggle to the extended or in toggleposition to thereby maintain the latch in latching position. The inwardmovement of the latch 63 and latch toggle 1 |-13 is limited bycooperating stop surfaces 85 and 81 formed on the adjacent ends of thetoggle members 1| and 13.

In the latching position of the latch 63, the toggle 1|13 isapproximately in dead center position, i. e., the knee pivot pin 8| islocated approximately on a line joining the axis of the pivot shaft 15and the axis of the pivot pin 69. In the embodiment shown, the center ofthe knee pivot pin 8| is located a small distance to the right of thiscenter line so that the toggle 1|13 is very slightly overset. It is tobe understood, however, that the toggle may be disposed exactly on deadcenter or slightly under set if desired and reliance placed on thespring 83 to maintain the latch in latching position.

The toggle member 13 is provided with a projection 89 adjacent its fixedpivot end which is disposed over the trip plunger of the trip device 25so as to be engaged and moved by the trip plunger to effect tripping ofthe breaker when the trip device is actuated. The projection 89 carriesan adjustable spring bumper 9| which is adapted to engage the frame I!when the latch is moved to latching position to absorb some of thekinetic energy of the moving latch parts. The spring bumper also assistsin initiating move ment of the latch parts to released position uponoperation of the trip device 25.

The trip device 25 comprises a solenoid having a stationary core 93, amovable core 95, and an energizing winding 9'1. A trip plunger rod 99 iscarried by the movable core 95 and extends up through aligned openingsin the stationary core 93 and the frame I "I. When the winding 9'! isenergized, the trip plunger 99 is moved upwardly by the core 95 andengages and moves the toggle member I3 in a counterclockwise directioncausing collapse of the toggle and movement of the latch 63 towardreleased position thereby eifecting release of the trip free roller 49and breaker lever 39.

A toggle locking lever 86 is provided for the purpose of preventing thelatch 63 from returning to latching position following release untilafter the trip free roller 49 has been automatically retrieved or resetto its normal position. This prevents the latch checking switch,hereinafter described, which is controlled by the latch from beingoperated more than one time for each opening operation of the breaker.The toggle locking lever 86 is pivotally mounted on the pivot pin 65 atthe side of the latch 63 and is biased in a clockwise direction, asviewed in Fig. 1, by the spring 83 which is anchored at one end to atailpiece of the toggle locking lever 86. A projection 88 of the togglelocking lever is disposed to be engaged by the end of the breaker lever39 which carries the trip free roller 49, so as to hold the togglelocking lever down in an inoperative position whenever the trip freeroller 49 is in its normal or latched position. The toggle locking lever86 is provided with another projection 90 which is adapted to be movedinto blocking relation in the path of the knee pivot pin BI of thetoggle II-l3 whenever the trip free roller 49 is away from its normalposition thereby preventing movement of the toggle I I'I3 and latch 63to latching position until the trip free roller 49 is retrieved tonormal position. The toggle locking lever 88 is shown in lookingposition in Fig. 1. When the trip free roller 49 is automaticallyretrieved to its normal position as shown in Fig. 4, the end of thebreaker lever 39 engages the projection 88 of the toggle locking lever86 and depresses the toggle locking lever thereby causing the projection90 thereof to be moved out of the path of the knee pivot pin 8I of thetoggle to permit the toggle and latch 63 to be moved to latchingposition by the spring 83. Fig. shows the position of the parts afterthe latch 63 has been moved to latching position in engagement with thetrip free roller 49. In

this position, the circuit breaker mechanism is fully reset and ready tobe reclosed.

A latch checking switch I03 is mounted on the frame IT at the side ofthe latching mechanism 23 and this switch is adapted to be operated inresponse to the movement of the latch 63 to check the position of thelatch. The switch I03 is biased to open circuit position by a spring(not shown) and is adapted to be closed by depressing a pushbutton I05which projects through the top of the switch casing. The switch I03 isheld closed only as long as the pushbutton I05 is held in depressedposition. The latch checking switch I03 is adapted to be operated inaccordance with the movement of the latch 63 by means of an arm I01which is secured to the shaft I5 of the toggle member I3. When the latch63 and toggle II'I3 move to latching position, the arm I01 depresses thepushbutton I05 closing the latch checking switch I03, and the switchremains closed as long as the latch 63 remains in latching position.

The latch checking switch is usually connected in series with theoperating coil of the reclosing relay and with an auxiliary switch ofthe breaker which is arranged to close when the breaker reaches openposition as disclosed in the copending application of Lloyd W. Dyer, et2.1., Serial No. 294,048, previously referred to. In such instance, theclosing solenoid cannot be energized to reclose the breaker until theoperating mechanism has been automatically reset and the latch 63 is inlatching engagement with the trip free roller 49. It has been found,however, that due to the high speed operation of the parts, the latch 63rebounds several times when it moves to latching position in engagementwith the trip free roller 49. These rebounds of the latch 63 causeundesired opening operations of the latch checking switch I03 and as aresult the operating coil of the reclosing relay does not effectsufficient energization of the closing solenoid I9 toinitiate automaticreclosing of the breaker until after the latch 63 stops rebounding andremains in latched position. This delay is longer than is desiredparticularly where high speed automatic reclosing is required. In othertypes of automatic reclosing circuit breaker systems, the latch checkingswitch in addition to controlling the reclosing relay also operates thecounting element of the reclosing relay, and in such instance if thelatch rebounds, the latch checking switch opens thereby causing thecounting element of the reclosing relay to falsely operate.Consequently, a reclosing relay set to cause a definite predeterminednumber of automatic reclosing operations of the breaker, would actuallycause a lesser number of reclosures because of faulty counting of thereclosing relay which was due to the rebound of the circuit breakeroperating mechanism latch.

In Figure 5 of the drawings I have illustrated a bound of the latch 63and the consequent false operation of the latch checking switch I03 isprevented by a weight which is loosely mounted to move with the latchand has a mass approximately equal to the effective free weight and massof the latch and the parts which move with the latch. In the embodimentof the invention illustrated, a metal weight I99 is loosely disposed ina recess or pocket III provided therefor in the toggle member I3. Themetal weight I99 is freely movable a limited amount in the pocket I IIrelative to the toggle member '59 in the direction of movement of themember I3, and the weight is retained in the pocket by a cover plate II3which is secured to the toggle member 1'3 over the open side of therecess or pocket III by a plurality of screws I I5.

The weight I09, as determined by experiment, should preferably have aweight and mass approximately equal to the effective free weight andmass of the movable latch parts comprising the latch 63 and its togglell-J3. The Weight should preferably be carried by the moving latch parthaving the longest travel and moving at the highest speed. Moreover, itis desirable that the weight should be mounted so as to move as nearlyas possible in a horizontal path to reduce the effects of gravity and soas not to materially affect the normal operating speed of the latchparts.

When the latch 63 is moved toward latching position by the spring 83,after retrieving of the trip free roller 49, the weight I09 at thisinstant is in its outermost position against the cover plate H3 as,shown in Fig. 4, but is still moving in a direction toward the latch 63.By the time the latch 63 and toggle member 13 start to rebound fromlatching position, the Weight I69 which is still moving inwardly towardthe latch strikes the toggle member 13 and overcomes the reboundmovement due to the momentum and mass of the weight. The rebound of thelatch 63 and toggle member 13 is thus prevented or reduced to such avery slight amount that the latch checking switch I03 will not be openedthereby.

While the invention has been disclosed in ac cordance with the patentstatutes, it is to be understood that various changes may be made inconstruction disclosed without departing from some of the essentialfeatures of the invention.

I claim as my invention:

1. In a circuit breaker having an operating member releasable to causeopening of the breaker, a movable latch for engaging and holding saidoperating member in operative position, said latch being biased tolatching position, trip means operable to move said latch to releasedposition to effect release of said operating member, an auxiliary switchcontrolled by said latch, and means operable to prevent rebound of saidlatch toward released position to thereby prevent false operation ofsaid auxiliary switch, said last mentioned means normally permittingmovement of said latch toward released position.

2. In a circuit breaker having a member releasable to cause opening ofthe breaker, a movable holding means for restraining said member inoperative position, spring means biasing said holding means to holdingposition, trip means operable to move said holding means to releasedposition to release said member, an auxiliary switch operated by saidholding means, means automatically effective to prevent return of saidholding means to holding position until said releasable member isreturned to its operative position, and means operable to preventrebound of said holding means toward released position when said holdingmeans is moved to holding position, said rebound preventing meanspermitting movement of said holding means to released position at allother times.

3. In a circuit breaker having a member releasable to cause opening ofthe breaker, a movable holding means for restraining said member inoperative position, spring means biasing said holding means to holdingposition, trip means operable to move said holding means to releasedposition, an auxiliary switch controlled by said holding means and meansoperable by the movement of said holding means to holding position foropposing rebound of said holding means toward released position tothereby prevent false operation of said auxiliary switch.

4. In a circuit breaker having a member releasable to cause opening ofthe breaker, a movable latch for engaging and restraining said member inoperative position, spring means biasing said latch to latchingposition, trip means operable to move said latch to released position,an auxiliary means controlled by said latch, means automaticallyeffective to prevent return of said latch to latching position untilsaid releasable member is returned to operative position, and meansmovable with said latch operable to oppose rebound of said latch towardreleased position to thereby prevent false operation of said auxiliarymeans.

5. In a circuit breaker having a member releasable to cause opening ofthe breaker, a movable latch for engaging and restraining said member inoperative position, spring means biasing said latch to latchingposition, trip means operable to move said latch to released position,an auxiliary switch controlled by said latch, and means comprising aweight of predetermined mass movable by said latch and operable tooppose rebound of said latch to thereby prevent false operation of saidauxiliary switch.

6. In a circuit breaker having a member releasable to cause opening ofthe breaker, a movable latch for engaging and restraining said member inoperative position, a toggle connected to said latch, spring meansconnected to said toggle for biasing said latch to latching position,trip means operable to effect movement of said latch to releasedposition to release said member, and means comprising a weight ofpredetermined mass movable with said latch and operable to preventrebound of said latch toward released position when said latch is movedto latching position.

'7. In a circuit breaker having a member releasable to cause opening ofthe breaker, a movable latch for engaging and restraining said member inoperative position, a toggle connected to said latch, spring meansconnected to said toggle for biasing said latch to latching position,trip means operable to effect movement of said latch to releasedposition to release said member, and means comprising a weight ofpredetermined mass carried by said latch toggle operable to preventrebound of said latch toward released position when said latch is movedto latching position.

8. In a circuit breaker having a member releasable to cause opening ofthe breaker, a movable latch for engaging and restraining said member inoperative position, a toggle connected to said latch, spring meansconnected to said toggle for biasing said latch to latching position,trip means operable to effect movement of said latch to releasedposition to release said member, and means comprising a weight ofpredetermined mass movable with said latch and operable to preventrebound of said latch toward released position when said latch is movedto latching position, said weight being mounted on said toggle forlimited movement relative thereto in the direction of movement of saidtoggle and having a mass approximately equal to the eifective mass ofsaid latch and toggle.

9. In a circuit breaker having an operating mechanism including a memberreleasable to cause opening of the breaker, a movable holding means forrestraining said member in operative position, spring means for biasingsaid holding means to holding position, trip means operable to causemovement of said holding means to released position to release saidmember, an

auxiliary control switch operated by the movement of said holding means,and means comprising a weight of predetermined mass movable with saidholding means operable to prevent rebound of said holding means tothereby prevent false operation of said auxiliary control switch.

10. In a circuit breaker having an operating mechanism including amember releasable to cause opening of the breaker, a movable latch forrestraining said member in latched position, spring means for biasingsaid latch to latching position, trip means operable to cause movementof said latch to released position to release said member, an auxiliarycontrol switch operated by the movement of said latch, and meanscomprising a weight of predetermined mass movable with said latchoperable to prevent rebound of said latch to thereby prevent falseoperation of said auxiliary control switch, said weight being movable alimited amount relative to said latch approximately in the direction ofmovement thereof.

11. In a circuit breaker having an operating mechanism including amember releasable to cause opening of the breaker, means comprising atoggle for restraining said member in an operative position, a springfor biasing said toggle to restraining position, trip means operable tocause collapse of said toggle to release said memher, an auxiliarycontrol switch operated by the movement of said toggle, and meansoperative to prevent rebound of said toggle to thereby prevent falseoperation of said auxiliary control switch.

12. In a circuit breaker having an operating mechanism including amember releasable to cause opening of the breaker, a pivoted latch forrestraining said member in latched position, a toggle connected at oneend to said latch, spring means connected to said toggle for biasingsaid latch to latching position, trip means operable to cause movementof said latch to released position to release said member, said memberbeing resettable to latched position following its release, an auxiliarycontrol switch operated by the movement of said latch, and meanscomprising a weight of predetermined mass movable with said latchoperable to prevent rebound of said latch to thereby prevent falseoperation of said auxiliary control switch.

13. In a circuit breaker having an operating mechanism including amember releasable to cause opening of the breaker, a pivoted latch forrestraining said member in latched position, a toggle connected at oneend to said latch, spring means connected to said toggle for biasingsaid latch to latching position, trip means operable to cause movementof said latch to released position to release said member, said memberbeing resettable to latched position following its release, an auxiliarycontrol switch operated by the movement of said latch, and meanscomprising a weight of predetermined mass carried by said toggle andmovable a limited amount relative thereto in the direction of movementof said toggle for preventing rebound of said latch to thereby preventfalse operation of said auxiliary control switch.

HARRY J. LINGAL,

